1. Field of the Invention
The present invention relates to a novel and improved assembly for axially positioning or "chocking" mill roll bearings and the like where such bearings must frequently be chocked, adjusted and unchocked to permit roll replacement and to assure maximum roll operating life.
2. Prior Art
Rolling mills include an array of parallel extending rolls which exert compressive rolling forces on metal feed stock, typically forming it into thinner elongated strip or plate configurations. The mill rolls have reduced diameter end regions called roll necks which are journaled for rotation by roller bearings supported in a mill stand. Adjustable bearing chocking devices hold the roller bearings in place and provide a means for axially adjusting bearing play.
The mill rolls, particularly the primary work rolls, must frequently be removed and reground. In some present day cold rolling mills, the work rolls have a useful life of only about 4 to 8 hours. In order to minimize mill down-time during roll replacement, it is desirable to provide a bearing chocking device which is easily installed, removed, and adjusted to effect proper chocking of the roller bearings. It is also desirable to provide a bearing chocking device which, for purposes of safety, minimizes the possibility of its becoming disengaged or loosening its pre-adjusted chocking position during operation.
Most known bearing chocking devices for mill rolls have included three annular components: a locking collar assembly which mounts in an annular groove on a roll neck, and a pair of rings threaded together to provide an annular assembly of adjustable length. The assembly of threaded rings is positioned between the locking collar and the bearing to be chocked, whereafter the rings are rotated to extend the length of the assembly until the bearing is properly chocked.
Known locking collar assemblies are either relatively complex, requiring substantial amounts of time to install and remove, or are relatively insecure and present safety concerns. One recently proposed locking collar provides two semi-annular members hinged together by a single hinge pin at one end and releasably coupled by a single threaded fastener at the other end. If either the hinge pin or the threaded fastener should fail, the collar drops off the mill neck.
Known threaded ring assemblies are expensive-to-machine structures that are not easily installed, removed and adjusted. Recent proposals to improve the configuration of these assemblies have called for additional modification of other surrounding structures such as the bearing retaining rings. Some proposals even require modification of the roll neck configuration. These modifications are expensive to effect and result in specially configured parts that cannot be used with standard bearing chocking devices.